Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that works. Can you open the Profile Manager and create a new profile and/or start in offline mode? *http://kb.mozillazine.org/Profile_Manager *https://support.mozilla.org/kb/Managing+profiles

Yes it works when i boot windows in safe mode with network support. And yes i can create a new profile and start in offline mode

What are the Firefox connection settings? *Tools > Options > Advanced : Network : Connection > Settings *https://support.mozilla.org/kb/Options+window+-+Advanced+panel If you do not need to use a proxy to connect to internet then try to select "No Proxy" if the "Use the system proxy settings" setting or one of the others doesn't work properly. See "Firefox connection settings": *https://support.mozilla.org/kb/Firefox+cannot+load+websites+but+other+programs+can ---- If booting in Safe mode works then it can be caused by your security software (firewall, anti-virus) or you may have malware. *http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx Autoruns Do a malware check with some malware scanning programs on the Windows computer.<br /> You need to scan with all programs because each program detects different malware.<br /> Make sure that you update each program to get the latest version of their databases before doing a scan. *http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware *http://www.superantispyware.com/ - SuperAntispyware *http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner *http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page *http://www.safer-networking.org/en/index.html - Spybot Search & Destroy You can also do a check for a rootkit infection with TDSSKiller. *http://support.kaspersky.com/viruses/solutions?qid=208280684 See also: *"Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked